WASHINGTON (AP) — The FBI warned law enforcement agencies ahead of last week's breach of the U.S. Capitol about the potential for extremist-driven violence, U.S. officials said, contradicting earlier statements that they were caught off guard by the assault by supporters of President Donald Trump.

Nearly a week after the riot, officials said they were combing through mountains of evidence and vowed to aggressively seek out those who perpetrated the brazen attack on the U.S. Capitol. Though most of the charges brought so far have been misdemeanors, acting U.S. Attorney Michael Sherwin said Tuesday the Justice Department was considering bringing sedition charges against some of the rioters, effectively accusing them of attempting to overthrow or defeat the government.

"This is only the beginning," Sherwin said. "We're going to focus on the most significant charges as a deterrent because, regardless of it was just a trespass in the Capitol or if someone planted a pipe bomb, you will be charged and you will be found."

The Justice Department has created a specialized strike force to examine the possibility of sedition charges, which could carry up to 20 years in prison. Officials said they were utilizing some of the same techniques in the riot probe as they use in international counterterrorism investigations, examining the money flow and movement of defendants leading up to the breach. Senate Minority Leader Chuck Schumer, a New York Democrat, called for the rioters to be added to a no-fly list, a tool most commonly associated with terrorisms investigations.

The statements by FBI and Justice Department officials on Tuesday were intended as both a defense of federal law enforcement preparations before the deadly riot and as a warning to participants. But they also raised new questions about the coordination across agencies for the Jan. 6 riot, which was sparked by Trump's calls for his supporters to fight Congress' vote confirming President-elect Joe Biden's victory.

In the immediate aftermath of the riot, some law enforcement officials, including the Capitol police chief, said they were unaware of serious concerns leading up to Jan. 6 and had prepared only for a free-speech protest.

But on Tuesday, The Washington Post reported on the existence of a Jan. 5 report from the FBI's field office in Norfolk, Virginia, that forecast, in detail, the chances that extremists could commit "war" in Washington the following day. Steven D'Antuono, the assistant director in charge of the FBI's Washington field office, said that once he received the Jan. 5 warning, the information was quickly shared with other law enforcement agencies through the joint terrorism task force.

D'Antuono was among the officials who suggested law enforcement had simply been caught off guard, saying on Friday: "There was no indication that there was anything other than First Amendment protected activity."

He did not explain the discrepancy in his statements, though he suggested Tuesday that the Norfolk warning was based on nonspecific information in terms of individual leads to investigate, characterizing it as a "thread on a message board" that was not attributable to any specific person.

In a statement Tuesday night, the FBI said the report's author had warned that the "FBI might be encroaching on free speech rights" in pursuing further action, and that the document itself did not necessarily associate the comments with a national security threat or crime. It highlighted D'Antuono's remarks at the news conference suggesting that without knowing the identity of the people whose words were cited in the report, there was not much that could be done with the information.

U.S. Capitol Police and other official didn't immediately respond to questions about their own initial assessments of the threat.

A U.S. defense official familiar with the discussions said Tuesday that Army Secretary Ryan McCarthy was not notified about the FBI warning.

The official, who spoke on condition of anonymity to discuss internal deliberations, said that it is unclear whether any defense or military officials heard about the notification from the FBI, but that statements in recent days from all the leaders indicate they weren't aware that violence of that level was expected at the Capitol.

Defense and National Guard officials, including McCarthy, have said in interviews over the past several days they were told by D.C. that they believed the protests would be similar to the ones on Nov. 14 and Dec. 12. And they said that federal law enforcement authorities said that there was activity on Twitter, but that they weren't expecting the level of violence they ultimately saw last Wednesday.

Even without intelligence from law enforcement, there had been ample warning about pro-Trump demonstrations in Washington. But Capitol Police did not bolster staffing and made no preparations for the possibility that the planned protests could escalate into massive, violent riots, according to several people briefed on the law enforcement response. Officials turned down help offered by the Pentagon three days before the riot.

When backup was finally requested, it took more than two hours for troops to mobilize near the Capitol. By then the mob had raged inside for more than four hours.

Once the mob began to move on the Capitol, a police lieutenant issued an order not to use deadly force, which explains why officers outside the building did not draw their weapons as the crowd closed in. Officers are sometimes ordered to keep their weapons holstered to avoid escalating a situation if superiors believe doing so could lead to a stampede or a shootout.

In this instance, it also left officers with little ability to resist the mob. In one video from the scene, an officer puts up his fists to try to push back a crowd pinning him and his colleagues against a door. The crowd jeers, "You are not American!" and one man tries to prod him with the tip of an American flag.

The rampage through the halls of Congress sent lawmakers of both parties and Trump's own vice president into hiding, as crowds called for Mike Pence's lynching for his role overseeing the vote count. The scene also undermined the hallmark of the republic — the peaceful transition of power. At least five people died, including one Capitol Police officer.

In a video statement released by the Justice Department, acting Attorney General Jeffrey Rosen said federal officials would have "no tolerance for any attempts to disrupt the peaceful transfer of power."

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Associated Press writer Lolita C. Baldor in Washington contributed to this report.